<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <link rel="stylesheet" href="css/bootstrap.min.css">
    <style>
        .row{
            margin-bottom: 20px;
        }
        .row .row{
            margin-top: 10px;
            margin-bottom: 0;
        }

        [class*='col-']{
            padding-top: 15px;
            padding-bottom: 15px;
            background-color: #eee;
            background-color: rgba(86, 61, 124, .15);
            border: 1px solid #ddd;
            border: 1px solid rgba(86, 61, 124, .2);
        }
    </style>
</head>
<body>
<div class="container">
    <div class="row">
        <div class="col-md-1">col-md-1</div>
        <div class="col-md-1">col-md-1</div>
        <div class="col-md-1">col-md-1</div>
        <div class="col-md-1">col-md-1</div>
        <div class="col-md-1">col-md-1</div>
        <div class="col-md-1">col-md-1</div>
        <div class="col-md-1">col-md-1</div>
        <div class="col-md-1">col-md-1</div>
        <div class="col-md-1">col-md-1</div>
        <div class="col-md-1">col-md-1</div>
        <div class="col-md-1">col-md-1</div>
        <div class="col-md-1">col-md-1</div>
    </div>
    <div class="row">
        <div class="col-md-3">col-md-3</div>
        <div class="col-md-3">col-md-3</div>
        <div class="col-md-3">col-md-3</div>
        <div class="col-md-3">col-md-3</div>
    </div>
<!--    偏移-->
    <div class="row">
        <div class="col-md-6 col-md-offset-3">col-md-6</div>
    </div>
<!--    嵌套-->
    <div class="row">
        <div class="col-md-9">
            <div class="col-md-1">col-md-1</div>
            <div class="col-md-1">col-md-1</div>
            <div class="col-md-1">col-md-1</div>
            <div class="col-md-1">col-md-1</div>
            <div class="col-md-1">col-md-1</div>
            <div class="col-md-1">col-md-1</div>
            <div class="col-md-1">col-md-1</div>
            <div class="col-md-1">col-md-1</div>
            <div class="col-md-1">col-md-1</div>
            <div class="col-md-1">col-md-1</div>
            <div class="col-md-1">col-md-1</div>
            <div class="col-md-1">col-md-1</div>
        </div>
        <div class="col-md-3">col-md-3</div>
    </div>
</div>
</body>
</html>